For conveying fluids under pressure, pipes are the backbone of any wastewater or water line system. Ductile iron pipe has been the industry standard for modern water and wastewater systems for nearly sixty years. Ductile iron pipe is available in various diameters from 2 inches up to 12 inches, and in lengths of 18 feet and 20 feet. Ductile iron pipe has been proven over the years to be strong, durable, and reliable.
Plastic pipes and more specifically, polyvinyl chloride (PVC) pipes were first introduced into the United States in the 1950s. However, due to health concerns and primitive manufacturing techniques, plastic pipe did not become a standard in the modern water and wastewater systems until the early 1980s. Plastic pipe continues to be an area of innovation for water and sewer pipes and its percentage of the total water pipe used in the United States grows each year. As cast iron and ductile iron water pipes age and develop leaks, they are commonly replaced with plastic pipes. Furthermore, the installation of plastic water pipes for new construction is becoming more common.
According to a recent study by the Environmental Protection Agency, there are currently over 1,000,000 miles of water mains in the United States. Ductile iron pipe represents about 24% of the pipe used in the United States to carry water and wastewater, while PVC pipe represents about 17%. Currently over 13,200 miles of water pipe are installed in the United States each year with approximately 48% of the newly installed pipe being ductile iron pipe and approximately 38% being PVC pipe. In addition to PVC, other types of plastics are used and are gaining acceptance in this field, including polyethylene, chlorinated polyvinyl chloride (CPVC), acrylonitrile butadiene styrene (ABS) and other polyolefins.
The conventional method of joining plastic pipes to ductile iron pipes is a time-consuming and labor-intensive process wherein a coupler is placed between a ductile iron pipe and a plastic pipe and a plurality of retaining bolts are used to lock the coupler in place, creating a transition between the ductile iron and plastic pipes. The ends of each pipe must be inserted into the coupling and then the plurality of retaining bolts must be tightened either by hand or with the aid of a tool or other mechanical device, all of which requires a significant amount of time and labor. Frequently, water pipes are installed in ditches that may be only 18 inches wide, and this increases the difficulty in installing pipe joints on long pipe runs.
It would be advantageous if a method and apparatus for connecting plastic pipe to ductile iron pipe without a complex coupler could be developed.